Thank you everyone, so much. There is a lot of comfort in all that you have written.
This really stuck with me:
A possible reason for saying and even feeling like this on some level is about having a sense of control. It sounds counter intuitive, but maybe if somehow your 'not being a good wife' contributed to an environment that 'caused' him to be unfaithful. then if you are now a 'good wife' you can effect that outcome.
In a way I can see how a driver might have been to mark your territory.
I said a similar thing to my H. shortly after discovery. In my mind I thought "So AP watch out because now I am back in my groove"
We 'know' that their affairs are about them. That even having been the most attentive wife would not have changed that outcome. but it is a natural and understandable reaction to wish if we just did something differently it would never have happened.
On a level I wonder if you were letting her know that his infidelity wasn't about her. That he didn't 'choose' her. And in some sense you were right. His actions had nothing to do with her, other than that she was available. She may as well have been a mirror. Because his affair was all about him.
I'm so very sad - but I don't feel alone. Thank you.